My 79 has begun to hesitate and/or sputter in the mid RPMs in 2nd and 3rd gear when cruising. When accelerating, it is fine. Can't seem to locate what 's causing it. Points, plugs, ignition wires, cap & rotor, condensor, fuel filter, fuel pressure regulator, ignition coil, air filter, vacuum hoses, have all been replaced recently, and timing, point gap, plug gaps, valve clearances have all been checked and rechecked. It sounds like it's misfiring, and the bus is driveable. Anyone have any ideas where to look next? Thanks as always for any and all help.
-Dave